Qualidade pós-colheita de azedinha (Rumex acetosa L.) submetida ao hidrorresfriamento e ao armazenamento sob atmosfera modificada

Abstract

Non-conventional vegetables are vehicles of vitamins, minerals, fiber and, not rarely, carbohydrates and proteins, besides bioactive compounds with antioxidant activity. However, due to the consumption pattern and world eating habits, these species have been losing space and their consumption has been increasingly restricted to traditional populations. Besides the reduction in consumption, there are few studies evaluating the influence of conservation techniques on the shelf life of non-conventional vegetables such as sorrel (Rumex acetosa L.). Thus, the objective of this study was to evaluate the effect of hydrocooling and modified atmosphere on the physical and chemical characteristics of sorrel during storage. The vegetables were obtained from a rural producer in the region of Lavras, Minas Gerais and the shelf life study was conducted in the Food Science Department of the Federal University of Lavras. In the first experiment, the vegetables were submitted to hydrocooling at 0 °C, 10 °C and 20 °C for 10 and 20 minutes in order to define the ideal parameters for the application of the technique. After hydrocooling, the samples were packed in flexible 100 μm thick polyethylene packages with zip lock type closure and stored in a cold chamber at a temperature of 10±1 °C, with a relative humidity of approximately 99 % for 10 days. In the second experiment, hydrocooling was applied using water at 20 °C for 10 minutes, according to the best results obtained in the first experiment. After the application of the technique the vegetables were packed in different packages in order to evaluate the effect of the modified atmosphere on its conservation during storage. The following packages were used: flexible polyethylene of 100 μm thickness with zip lock type closure (ziplock); flexible low density polyethylene of 50 μm sealed (sealed) and rigid post-consumer recycled polyethylene terephthalate (PET/PCR) with snap-on lid of the same polymer (control). The samples were stored in a cold room at a temperature of 5±1 °C with a relative humidity of approximately 99 % for 10 days. In both experiments analyses of mass loss, respiratory activity, CO2 monitoring inside the package, coloration, soluble solids, pH, titratable acidity, total chlorophyll, total carotenoids, vitamin C, total phenolics and antioxidant activity were performed. The samples were evaluated at 0, 2, 4, 6, 8 and 10 days of storage. All the results were submitted to variance analysis and compared by the Scott Knott test at 5% significance level. Polynomial regression plots and self-organizing Kohonen maps (ANN/KSOM) were also obtained to analyze the results. The effect of hydrocooling was observed in the reduction of mass loss and in the maintenance of chlorophyll, vitamin C and phenolic contents, with emphasis on the treatments hydrocooled at 20 °C. The effect of modified atmosphere combined with hydrocooling was also beneficial. The zip lock and sealed packages determined lower losses of mass and better conservation of the vegetable throughout the ten days of storage compared to the control treatment.